About SLR cameras and 50mm lenses

1. Low and mid-range machines are equipped with lenses, while high-end machines are not equipped with lenses. On the one hand, people who buy low-end phones are newbies and probably don’t have any lenses, so equipping them with them means it is convenient to make money and the merchants are not stupid. High-end cameras are all old-fashioned, who will buy your lenses?

2. The reason why the 50mm lens is a lens is because it sees the same world as our eyes. The telephoto lens is the eye of an eagle, and the wide-angle lens is the eye of a fish. Eyes can all be focused. If you think of the lens as an eye, you will understand. Your eyes can see distant views and close-up views clearly because there are muscles in your eyes to adjust the focus, and there are motors in the camera to adjust the focus.